| 1. |
- Kehoe, Laura, et al.
(author)
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Make EU trade with Brazil sustainable
- 2019
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Journal article (other academic/artistic)
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| 2. |
- Johnson, Mark D., 1954, et al.
(author)
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Unraveling Scandinavian geomorphology: the LiDAR revolution
- 2015
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In: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 137:4, s. 245-251
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Journal article (peer-reviewed)abstract
- In the observational sciences, technical advances are often followed by dramatic increases in scientific discoveries and improved theory. Leuwenhoek’s microscope and Galileo’s telescope gave us a “better look” at the microworld and the cosmos, which led to revolutions of past paradigms. In geomorphology and landscape analysis, similar advances have accompanied new maps and new mapping techniques. The first accurate globes, where the puzzle-piece fit of the southern continents was quickly noticed, were soon followed by the first mention of what would be continental drift. The first topographic maps were accompanied by similar shifts in thinking. For example, accurate topographic maps of the western US brought about the realization that even in arid regions, fluvial erosion can be the dominant landscaping force. Aerial photography provided a similar advance in observation, mapping and understanding. Satellite imagery of the Earth and other planets has dramatically revealed the geomorphic processes operating in inaccessible places, for example meteor impacts, volcanism and the importance of eolian and fluvial processes. Recent observations of Pluto and Mars attest to this fact. Satellite imagery also led to a revolution in glacial geomorphology by providing continent-wide images of features heretofore unnoticed, for example the palimpsest flow indicators of the Laurentide Ice Sheet (Boulton & Clark 1990). In the 90s, the production of digital elevation models (DEMs) and the development of geographic information system (GIS) tools allowed for new highly quantitative analysis of landscapes. The advent of LiDAR (Light Detection and Ranging) technology is poised to provide a similar rapid advance in observations and the potential for significant advances in geomorphic theory. We see that the ever increasing use of LiDAR technology is creating a similar leap forward in geomorphology, and this issuie celebrates that.
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| 3. |
- Ojala, A. E. K., et al.
(author)
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Ice-sheet scale distribution and morphometry of triangular-shaped hummocks (murtoos): a subglacial landform produced during rapid retreat of the Scandinavian Ice Sheet
- 2019
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In: Annals of Glaciology. - : Cambridge University Press (CUP). - 0260-3055 .- 1727-5644. ; 60:80, s. 115-126
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Journal article (peer-reviewed)abstract
- High-resolution digital elevation models of Finland and Sweden based on LiDAR (Light Detection and Ranging) reveal subglacial landforms in great detail. We describe the ice-sheet scale distribution and morphometric characteristics of a glacial landform that is distinctive in morphology and occurs commonly in the central parts of the former Scandinavian Ice Sheet, especially up-ice of the Younger Dryas end moraine zone. We refer to these triangular or V-shaped landforms as murtoos (singular, `murtoo'). Murtoos are typically 30-200 m in length and 30-200 m in width with a relief of commonly <5 m. Murtoos have straight and steep edges, a triangular tip oriented parallel to ice-flow direction, and an asymmetric longitudinal profile with a shorter, but steeper down-ice slope. The spatial distribution of murtoos and their geomorphic relation to other landforms indicate that they formed subglacially during times of climate warming and rapid retreat of the Scandinavian Ice Sheet when large amounts of meltwater were delivered to the bed. Murtoos are formed under warm-based ice and may be associated with a non-channelized subglacial hydraulic system that evacuated large discharges of subglacial water.
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| 4. |
- Peterson, Gustaf, 1982, et al.
(author)
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Genesis of hummocks found in tunnel valleys: an example from Horda, southern Sweden
- 2018
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In: Gff. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 140:2, s. 189-201
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Journal article (peer-reviewed)abstract
- In the south-central sector of the former Fennoscandian Ice Sheet, imprints of the sub-glacial hydrological system are present as glaciofluvial corridors, formed by glacial meltwater at the ice-bed interface during the BOlling-AllerOd warm period. Many of these are interpreted as tunnel valleys and are commonly characterized by hummocks on their valley floors. Contemporary ice sheets produce increased amounts of meltwater as a consequence of global warming, and occasionally it is observed that meltwater is suddenly released from supra- and subglacial lakes, suggesting a highly dynamic subglacial hydraulic system. Studies of the imprints and deposits from such systems on formerly glaciated terrain can expand our knowledge of ice-sheet response to increased meltwater production. Here, we study sediments exposed in two hummocks within the tunnel valley at Horda, south Sweden. One of the investigated hummocks is superposed by a small esker. This hummock consists of a diamict interpreted as a subglacial traction till, observed to be overlain by esker sediment. A second hummock displays deformed sediment at its base, which is glaciotectonically intercalated with above-lying diamict, a sub-glacial traction till. The sub-till sediments, interpreted as proglacial outwash, were deformed by overriding ice. The sediment was dated using optically stimulated luminescence (OSL), inferring a late MIS 4 or early MIS 3 age, congruent with other observations of sub-till sediments in south Sweden. The investigated hummocks on the floor of the Horda tunnel valley are interpreted to have been formed by sub-glacial fluvial erosion simultaneous with tunnel valley formation, most probably during the latest deglaciation of the area.
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| 5. |
- Peterson, Gustaf, 1982, et al.
(author)
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Glacial geomorphology of the south Swedish uplands – focus on the spatial distribution of hummock tracts
- 2017
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In: Journal of Maps. - : Informa UK Limited. - 1744-5647. ; 13:2, s. 534-544
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Journal article (peer-reviewed)abstract
- We present the first comprehensive glacial-landform map of the south Swedish uplands (SSU), deglaciated 15–13ka ago, using one consistent method and dataset; a Light Detection and Ranging-derived digital elevation model. In particular, this map focuses on the spatial distribution of hummock tracts. The distribution of hummock tracts reinforces previous thinking of a broad lobate east–west zone of hummocks across the southern part of the SSU. But this map also reveals a pattern of hummock tracts confined in what we call hummock corridors that have a radial pattern sub-parallel to the overall ice-flow direction. Hummocks occur in a wide variety of morphologies, but we also show the distribution of two distinct forms: V-shaped hummocks and ‘ribbed moraine’. Cross-cutting relationships between hummocks and glacial lineations indicate a more complex chronology than previously suggested. In places, lineations are overlain by hummocks and in other places hummocks are overlain by lineations. Additionally, directional variation of glacial lineations together with a complex end-moraine pattern suggests a dynamic ice sheet with multiple small lobes. Finally, mapped end moraines help to better correlate the deglacial timescales of western and eastern Sweden.
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| 6. |
- Peterson, Gustaf, 1982, et al.
(author)
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Hummock corridors in the south-central sector of the Fennoscandian ice sheet, morphometry and pattern
- 2018
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In: Earth Surface Processes and Landforms. - : Wiley. - 0197-9337 .- 1096-9837. ; 43:4, s. 919-929
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Journal article (peer-reviewed)abstract
- Subglacial conditions strongly influence the flow of ice-sheets, in part due to the availability of melt water. Contemporary ice sheets are retreating and are affected by increased melting as climate warms. The south Swedish uplands (SSU) were deglaciated during the relatively warm BOlling-AllerOd interval, and by studying the glacial landforms there it is possible to increase the understanding of the subglacial environment during this period of warming. Across the study area, vast tracts of hummocks have long been recognized. However, recent mapping shows a pattern of elongated zones of hummocks radially oriented, hereafter referred to as hummock corridors'. Morphometric parameters were measured on the hummock corridors using a 2m horizontal resolution digital elevation model. Corridor width varies between 0.2 and 4.9km and their length between 1.5 and 11.8km. A majority of hummock corridors are incised in drumlinised till surfaces. The pattern of hummock corridors shows a clear relation to the overall ice-flow. Further, hummock corridors do not follow topographic gradients, and in at least one place an esker overlies hummocks on the corridor floor. The lateral spacing of hummock corridors and corridor morphology are similar to tunnel valleys, eskers and glaciofluvial corridors reported elsewhere. Such relationships support a subglacial genesis of the corridors in the SSU by water driven by the subglacial hydraulic gradient and that hummock corridors are forms that can be identified as tunnel valleys and glaciofluvial corridors (GFC). Ages were assigned to hummock-corridor cross-sections from a deglacial reconstruction of the Fennoscandian Ice Sheet. By comparing the frequency of corridors per age interval with climate variations from a Greenland ice core, we hypothesize that an increase in the number of corridors is related to the BOlling-AllerOd warming, indicating a higher rate of delivery of surface melt water to the bed at this time. Copyright (c) 2017 John Wiley & Sons, Ltd.
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| 7. |
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| 8. |
- Öhrling, Christian, et al.
(author)
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Glacial geomorphology between Lake Vänern and Lake Vättern, southern Sweden
- 2020
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In: Journal of Maps. - : Informa UK Limited. - 1744-5647. ; 16:2, s. 776-789
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Journal article (peer-reviewed)abstract
- The glacial geomorphology between the lakes Vänern and Vättern is presented on a 1:220,000 scale, LiDAR-based map covering approximately 18,000 km2. Fifteen landform units have been mapped; end moraines, De Geer moraines, drumlins, crag-and-tails, hummock tracts and corridors, irregular ridges, murtoos, eskers, deltas/sandur, outwash complexes, meltwater channels, boulder bars/sheets, the Timmersdala ridge, raised shorelines, sand dunes and prominent landslide scars (the last three are post-glacial). The area includes moraines associated with the Younger Dryas cold interval and drainage deposits of the Baltic Ice Lake. Additionally, the map reveals previously undetected geomorphic features including (1) murtoos, (2) abundant traces of meltwater erosion manifested as channels and hummock corridors, (3) laterally extensive end-moraine systems (the Remmene and Kungslena ice-margin positions) and (4) the distinct lobate shape of end moraines formed above the highest shoreline. This map provides a uniform base for future use in georesources, paleo ice-sheet modelling, geologic history, and geoconservation. © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of Journal of Maps.
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